RESUMO
Tropical forests of Amazonia play a major role in controlling the composition of the earth's atmosphere. Natural ecosystems of Amazonia contribute significant portions to the global budgets of the greenhouse gases methane and nitrous oxide. Amazon forest vegetation contributes to regional atmospheric chemistry as an important source of reduced gases such as volatile organics and carbon monoxide. The forest soils produce nitric oxide. Recent trends in land use change have led to increases in the sources of nitrous oxide and methane. The ozone precursor nitric oxide is internally recycled under forest conditions while deforestation leads to larger net emissions. We have limited knowledge of biosphere-atmosphere exchange of trace gases in Amazonia. However, recent advances in instrumentation approaches and the evolution in the design of interdisciplinary field campaigns enhance the prospects for successful study of this area in earth system science.